Liquid ring pumps are used to pump a variety of gases, however their typical materials of construction (e.g. stainless steel, cast iron, brass, etc.) precludes their long term use with strongly corrosive or reactive gases (i.e. acidic, basic, oxidising or reducing gases). Known liquid ring pumps have been made from exotic materials such titanium, ceramics and polymers, however, not only can these materials be costly but it is difficult to manufacture pumps in these materials with the required close dimensional tolerances between certain components, for example the rotor and the stator.
During the evacuation of some semiconductor manufacturing processes, for example plasma etch, the effluent gas stream produced is chemically reactive with, or soluble in, the service liquid (typically water) in the liquid ring pump. This generates a corrosive service liquid and thus corrosion products from the reaction of said corrosive service liquid with the internal workings of the pump. Such corrosion products can cause additional corrosion and abrasion within the pumping arrangement.
The discussion above is merely provided for general background information and is not intended to be used as an aid in determining the scope of the claimed subject matter. The claimed subject matter is not limited to implementations that solve any or all disadvantages noted in the background.